Disclosed herein is a method for determining the amount of media on an elevator that supports a media stack in an image production device, as well as corresponding apparatus and computer-readable medium.
In conventional finishing devices and feeders in image production devices, paper elevator position control generally involves stack height switches, corner sensors, and comb brackets with multiple transmissive sensors/algorithms to determine elevator position and direction. These methods require an elevator to initialize (or home) at some position which is usually at the top or bottom of travel. They measure position in the middle of travel by counting from the home position using stepper motor steps or sensor steps using a linear encoder. As an example, some image production devices use a comb bracket and three sensors to identify motion and upper and lower position only. The sensors are located on the elevator that detect transitions on a “comb bracket” located at the back of the frame. Often this process requires the elevator to travel to the bottom (or top) of its range to home, and then to move to the desired intermediate position during printer cycle up. This method takes a long time and several sensors are needed to identify elevator location (limited capability) and elevator motion.